AHJ: Current LDL guidelines may not be low enough to cut MI risk

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Nearly 75 percent of patients hospitalized for a heart attack had cholesterol levels that would indicate they were not at high risk for a cardiovascular (CV) event, based on the current national cholesterol guidelines, according to a study published in the January issue of the American Heart Journal.

These patients had low-density lipoprotein (LDL) cholesterol levels that met current national cholesterol guidelines, and close to half had LDL levels classified in guidelines as optimal (less than 100 mg/dL), according to the study’s principal investigator Gregg C. Fonarow, MD, professor of CV medicine and science at the David Geffen School of Medicine at the University of California at Los Angeles.

While the risk of CV events increases substantially with LDL levels above 40–60 mg/dL, the current national cholesterol guidelines consider LDL levels less than 100–130 mg/dL acceptable for many individuals. The guidelines are thus not effectively identifying the majority of individuals who will develop fatal and non-fatal CV events, according to the study's authors.

Researchers also found that more than half of patients hospitalized for a MI had poor high-density lipoprotein (HDL) cholesterol levels, according to national guidelines.

The study suggests that lowering guideline targets for LDL cholesterol for those at risk for CV disease, as well as developing better treatments to raise HDL cholesterol, may help reduce the number of patients hospitalized for MI in the future.

Fonarow and colleagues used a national database, sponsored by the American Heart Association's (AHA) Get with the Guidelines program, to analyze data from 136,905 patients hospitalized for a MI nationwide between 2000 and 2006, whose lipid levels upon hospital admission were documented, and who accounted for 59 percent of total hospital admissions for MI.

While the risk of CV events increases substantially with LDL levels above 40–60 mg/dL, the current national cholesterol guidelines consider LDL levels less than 100–130 mg/dL acceptable for many individuals. The guidelines are thus not effectively identifying the majority of individuals who will develop fatal and non-fatal CV events, according to the study's authors.

Researchers also found that more than half of patients hospitalized for a MI had poor high-density lipoprotein (HDL) cholesterol levels, according to national guidelines.

The study suggests that lowering guideline targets for LDL cholesterol for those at risk for CV disease, as well as developing better treatments to raise HDL cholesterol, may help reduce the number of patients hospitalized for MI in the future.

Among individuals without any prior cardiovascular disease or diabetes, 72.1 percent had admission LDL levels less than 130 mg/dL, which is the current LDL cholesterol target for this population. Thus, the investigators said that the vast majority of individuals having their first MI would not have been targeted for effective preventative treatments based on the criteria used in the current guidelines.

The team also found that half of the patients with a history of heart disease had LDL cholesterol levels lower than 100 mg/dL, and 17.6 percent of patients had LDL levels below 70 mg/dL, which are guideline targets for LDL cholesterol in those at fair risk and at high risk for CV disease, respectively.

The study also showed that HDL cholesterol levels have dropped in patients hospitalized for MI the past few years, possibly due to increasing rates of obesity, insulin resistance and diabetes.

Researchers found that 54.6 percent of patients had HDL levels below 40 mg/dL. Developing more effective treatments to boost HDL levels may help reduce the number of patients hospitalized for MI, according to the authors.

“We found that less than 2 percent of heart attack patients had both ideal LDL and HDL cholesterol levels, so there is room for improvement,” Fonarow said.

Fonarow said that only 59 percent of patients in the database had their lipid levels checked upon admission, which should be increased, since these early measurements can often help guide treatment decisions.

He also noted that only 21 percent of patients in the study were taking lipid-lowering medications before admission, despite almost half having a prior history of CV events, which would prompt treatment.